1. Field of the invention
The invention concerns drier drums, in particular drier drums for papermaking machines, for the textile industry and the like.
2. Description of the Prior Art
Known drying drums are generally heated by steam fed under pressure into their enclosure; different heating cycles are possible if the pressure of the input steam is modulated.
In applications where it is necessary to modify the drying capacity in each section along all the length of the "table" of the drum, to provide for controlling the moisture profile or, to use the converse concept, the dryness of the product to be dried (this is often the case in the field of papermaking), there are currently numerous possibilities:
to add steam blower manifolds outside the drum; this solution is somewhat impractical and difficult to adjust;
to integrate electrical heating elements into the drum; in the event of irregular or defective functioning it is necessary to demount a large part of the drum to service the complementary heating device;
to create electromagnetically induced Eddy currents outside or inside the drum cylinder; this solution implies a deformation of the ideal shape of the drum cylinder.
An object of the invention is to remedy these disadvantages and to enable known drier drums to be retrofitted after manufacture with a heating device for controlling the profile subject to detail or at most limited modifications.